Nystagmus Flashcards
sensation of environmental movement
oscillopisa
abnormal fast movements of the eyes away from fixation without a slow phase
saccadic intrusions (or saccadic oscillations)
nystagmus is named for the direction of ____
the fast phase
Match the type of nystagmus with the common cause:
- linear
- exponential increase in velocity of slow phase
- exponential decrease in velocity of slow phase
- Pendular
- vestibular nystagmus
- congenital nystagmus
- gaze-evoked nystagmus
- congenital or acquired nystagmus
nystagmus at 50 degrees horizontal?
normal past 45 degrees
T or F regarding congenital nystagmus:
- always presents before 1 year
- patients often have oscillopsia
- almost always conjugate and horizontal
- nystagmus is usually amplified by fixation
- there frequently is a null point
- can be jerk or pendular
- diminished by convergence
- present in sleep
- 50% have strabisumus
- false; usually present by first few months but may take several years
- false; they never do
- true
- true
- true
- true
- true
- false; not present in sleep
- false; 15% have strabismus
classic OKN findings in congenital nystagmus
reversal of normal response; slow phase follows opposite direction of rotation
visual acuity much better with two eyes than either eye individually, and nystagmus noted only with monocular occlusion. diagnosis, direction of nystagmus, and other common findings
latent nystagmus. fast phase beats away from the occluded eye. often with esotropia and DVD
monocular vertical nystagmus in a child with ipsilateral APD
neuroimage; likely optic nerve or chiasmal glioma
1 -year old with intermittent, binocular, very small amplitude, high frequency, horizontal, pendular nystagmus: diagnosis, workup, risk factors, prognosis, other classic findings
spasmus nutans MRI to r/o mass blacks and hispanics, low socioeconomic status benign and resolves after several years head nodding and abnormal head posturing
What is Alexander’s law?
amplitude of nystagmus will increase in the gaze of the direction of the fast-phase of the nystagmus
Inability to maintain eccentric fixation with slow drift away from gaze and saccadic correction in direction of gaze: diagnosis, pathophys, and causes
Gaze-evoked nystagmus, caused by dysfunction of the neural integrator. For horizontal gaze, this is the nucleus prepositus hypoglossi and medial vestibular nuclei. For vertical gaze, the interstitial nucleus of Cajal is involved. Etiologies include ethanol, anticonvulsants, sedatives, hypnotics. If asymmetric, then ipsilateral brainstem or cerebellar lesion is likely. Also can be caused by extraocular myopathies and myasthenia
right beating nystagmus after returning to fixation following prolonged right gaze? causes?
rebound nystagmus; cerebellar disease
a left-sided peripheral vestibular lesion will produce a ____ gaze bias and _____ nystagmus
left gaze bias (damaged left vestibular output from the neural integrator projects to contralateral PPRF, leading to loss of tonic output to the right; therefor eyes will drift leftward) and a right-beating nystagmus
T or F regarding peripheral vestibular nystagmus:
- vertigo is severe
- tinnitus and hearing loss are common
- horizontal nystagmus with torsion is rare
- pure vertical or torsional nystagmus is fairly common
- acute symptoms last a few days but remit over a few more days
- visual fixation worsens the nystagmus
- true
- true
- false; horizontal nystagmus with torsion is common and without torsion is rare
- false; rare
- false; acute symptoms do occur over a few days, but it may take weeks to months for symptoms to remit
- false; fixation improves nystagmus
What is Brun’s nystagmus?
Produced by a large cerebellopontine tumor, initially manifests as a peripheral vestibular nystagmus with ipsilateral gaze bias and contralateral jerk nystagmus, but as the tumor grows and compresses the ipsilateral brainstem, the horizontal integrators are affected and the patient will have difficulty maintaining ipsilateral gaze. Thus, on gaze towards the lesion, there will be a lower-frequency gaze evoked nystagmus, and on gaze away from the lesion there will be a higher-frequency vestibular nystagmus
most common form of central vestibular nystagmus? location of lesions causing this? most common structural cause of this?
downbeat nystagmus; cervical medullary junction; Arnold Chiari type I
antibodies against what structure have been linked to down beat nystagmus?
glutamic acid decarboxylase (thus affecting GABAergic neurons that normally suppress the flocculus)
down beat nystagmus is worse in what gaze?
down gaze (in accordance with Alexander’s law); in particular, tends to be worse on down gaze to either side
Most common location of lesions for:
- downbeat nystagmus
- upbeat nystagmus
- periodic alternating nystagmus
- ocular bobbing, opsoclonus, ocular flutter
- convergence-retraction “nystagmus”
- see-saw nystagmus
- monocular nystagmus of childhood
- cervical-medullary junction
- posterior fossa
- cerebellum (nodulus)
- pons
- dorsal midbrain (i.e. pretectum)
- parasellar/diencephalon
- optic nerve, chiasm, or hypothalamus
length of complete cycle for periodic alternating nystagmus
2-4 minutes
continuous, rhythmic, pendular nystagmus along with synchronous facial spasms. also present during sleep: diagnosis and classic MRI finding
oculopalatal myoclonus; hypertrophy of the inferior olivary nucleus
common cause of see-saw nystagmus?
craniopharyngioma
examples of saccadic intrusions with and without normal saccadic intersaccadic intervals
with: square-wave jerks
without: opsoclonus, ocular flutter, voluntary flutter
opsoclonus v ocular flutter. what must you rule out as an etiology for these in kids and adults?
- ocular flutter: very high frequency, small amplitude horizontal movements
- opsoclonus: similar high frequency but larger amplitude and multidirectional
- kids: r/o neuroblastoma (paraneoplastic)
- adults: r/o small cell can lung, breast or ovarian cancer (paraneoplastic)
ocular flutter v voluntary flutter
voluntary flutter is induced by convergence and is often accompanied by eyelid flutter and facial grimacing. episodes rarely last longer than 10-12 seconds.
